#define _CRT_SECURE_NO_WARNINGS 1
//F=Amax/(Bmax+Cmax)
#include<stdio.h>
float max3(float a, float b, float c)
{
    if (a > b && a > c)
        return a;
    if (b > c && b > a)
        return b;
    if (c > b && c > a)
        return c;
    return a;
}
int main()
{
    float a = 0;
    float b = 0;
    float c = 0;
    scanf("%f %f %f", &a, &b, &c);
    float m = 0.0;
    float a1 = max3(a + b, b, c);
    float a2 = max3(a, b + c, c);
    float a3 = max3(a, b, b + c);
    m = a1 / (a2 + a3);
    printf("%.2f", m);
    return 0;
}
